1. Field of the Invention
The present invention relates generally to systems for controlling and improving the performance of power water craft by integrating the utilization of aerodynamic effects with the utilization of hydrodynamic effects, and more particularly by enabling these utilizations of aerodynamic and hydrodynamic effects to be alterable, and where said alterable utilizations are capable of functioning while the watercraft is in operation.
2. Related Art
Efforts to improve the technologies utilized for marine transportation probably date back to the very advent of marine transportation. Among the more common of these types of attempts are those that strive to improve a boat's velocity of travel, either in terms of its absolute speed or its efficiency at a given speed, as well as those that attempt to enhance a boat's controllability at a given speed. In the present context, the term “boat” will be used generically to connote virtually any form of marine transportation, despite the convention in certain circumstances to apply this term with a more limited range of meaning. Typical ways to improve a boat's absolute speed include boosting the power of a motor boat's engine(s) and reducing the boat's weight. Usual means employed to increase a boat's efficiency include modifing hull shapes and surface coatings to lessen the boat's drag in the water. Methods of enhancing a boat's controllability have customarily involved systems that utilize hydrodynamic effects, such as rudders.
Whatever the speed with which a boat travels across the water, hydrodynamic factors will have a significant impact upon the boat's performance. Among the more critical of these factors are a boat's displacement, and how that displacement may vary with the boat's speed of travel, as well as the water environment that the boat is traveling through, with wave conditions and currents being foremost among these factors. The effects of hydrodynamic factors are also not static for a given boat and set of water conditions, since these effects will vary greatly depending on, among other things, the speed the boat is traveling and the direction the boat is heading relative to the predominant directions of the major waves and currents at that time and place. As the boat accelerates, it will usually ride higher in the water, with a lesser overall dynamic displacement, and the contact area between the boat and the water is also usually lessened and moved more towards the rear of a boat (for a customary rear drive arrangement).
Hydrodynamic factors are one of the major issues that impact on hull shape designs. The classic monohull V-bottom shape has the virtue of being able to lessen the impact of higher wave heights, but at the cost of relatively greater displacements, and hence less efficiency as the boat's speed increases. An alternative approach is to employ what are broadly referred to as multi-hull shapes, such as catamarans and trimarans. While these hull shapes may have a lesser ability to mitigate the effects of larger waves, they present other advantages that are particularly beneficial for higher speed boat travel. Multi-hulls tend to have decreased dynamic displacements, and they tend to reduce their hydrodynamic drag more quickly as their speed increases than would a comparable monohull V-bottom at the same speed. In the present context, the technologies described herein will be generally addressed to applications for catamarans, but it should be understood that this is merely for reasons of expediency of discussion, since the technologies discussed herein in reference to catamarans are also applicable to other types of multi-hulls and monohulls, with suitable modifications that will be readily apparent to those of skill in the art.
One significant effect that enables a catamaran to reach high speeds more quickly and efficiently than a monohull is due to the airflow into, and through, a catamaran's tunnel. As the catamaran picks up speed, the air pressure in the catamaran's tunnel increases, thereby providing a degree of lift to the boat and lessening its drag in the water. Hence, catamarans are often able to reach a planning attitude faster than a comparable V-hull does. This air-pressure buoyancy effect illustrates that aerodynamic factors can also exert significant effects on a boat traveling at speed. The relative importance of aerodynamic effects only increases with speed, so that at very great velocities the importance of the aerodynamic effects on a boat's performance can rival or exceed the importance of hydrodynamic effects. Aerodynamic effects such as the aerodynamic lift in a catamaran's tunnel at speed can also present significant impediments to maintaining optimal control. The angle of attack that a catamaran travels at can be critical, as becomes apparent in instances where a catamaran experiences a blow-over due to its attaining too great a pitch angle relative to the horizontal. However, if the pitch angle becomes too small, the boat may lose efficiency (and hence speed) and it may even nose dive into the next wave. Since wind and wave conditions are constantly varying, and boats typically change headings, there is an unmet need for a system that can adjust to both hydrodynamic and aerodynamic factors in an integrated manner, and that can accomplish these integrated adjustments in real time as the boat is in motion.
One prior art attempt to mitigate the risks of a catamaran flipping over at high speed is disclosed in J. K. Morris, U.S. Pat. No. 4,944,240 wherein the inventor patented a pair of cutout vents in the rearward roof portion of the tunnel. These vents are intended to provide a means for increased air escape from the tunnel of a catamaran when the catamaran's bow raises too high. This system is static and is essentially a variation in the topography of the tunnel that is intended to primarily become effective only when the boat is in danger of flipping over.
A prior art technology that is more germane to the present invention is a tunnel-flap innovation (not patented) invented by the present applicants. The tunnel-flap is a primarily planar element that depends rearwardly from the lower rearmost portion of the center section of a catamaran's transom that meets the tunnel roof, and is attached to the transom at the tunnel flap's leading edge. The attachment of the tunnel flap to the catamaran functions as a hinge with a horizontal rotational axis that runs parallel to the catamaran's transom, and enables the tunnel flap to be selectively raised or lowered to thereby provide the capability of selectively restricting the flow of air from the catamaran's tunnel to increase dynamic air pressure in the tunnel and further provide the capability of extending the effective aerodynamic length of the tunnel. The tunnel flap also moves the aerodynamic center of lift aft as its trailing edge is lowered. At lower speeds, the tunnel flap can be lowered so as to increase the rate at which air pressure in the tunnel builds up and thereby hasten the process of bringing the catamaran into a planing attitude. Once at higher speeds, the tunnel flap's position can be modified, depending on the conditions, to improve or control the catamaran's performance. While providing an additional degree of control of aerodynamic effects, the tunnel flap is an add-on component that can only modify the existing catamaran's aerodynamic and hydrodynamic properties to a limited degree. A more desirable system would enable the operator of a boat to alter a variety of control elements either individually or in varying combinations, even while operating at high speeds. Such a system would provide the capability of tailoring a boat's performance to differing conditions and criteria, and thereby facilitate optimizing the boat's performance for speed, efficiency, controllability, and safety.